#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "util/map.h"
#include "util/versie.h"

static void usage(FILE *f) {
  fprintf(f,
      "Gebruik: tak [-hV] <bestand...>\n"
      "\n"
      "Schakel bestanden aaneen naar standaard uitvoer omgekeerd.\n"
      "\n"
      "  -h    Toon deze hulptekst\n"
      "  -V    Toon versienummer\n");
}

// Returns pointer to argument array containing the file names
static char** parse_options(int argc, char **argv) {
  int opt;
  while ((opt = getopt(argc, argv, "hV")) != -1) {
    switch (opt) {
      case 'h':
        usage(stdout);
        exit(0);

      case 'V':
        drukkedoos_print_versie(stdout, "tak");
        exit(0);

      case '?':
        usage(stderr);
        exit(1);
    }
  }

  return argv + optind;
}

struct state {
  char *buf;
  size_t sz;
};

static void process(struct state state) {
  char *lstart, *lend;
  lend = &state.buf[state.sz - 1];

  while (lend > state.buf) {
    if (*lend == '\n') {
      lend--;
    }

    lstart = lend;
    while (*lstart != '\n' && lstart != state.buf) {
      lstart--;
    }
    if (lstart != state.buf) {
      lstart++;
    }

    fwrite(lstart, 1, lend - lstart + 2, stdout);

    lend = lstart-1;
  }
}

static char *read_stdin(size_t *sz) {
  const size_t CHUNK_SIZE = 4096;

  size_t cap = CHUNK_SIZE;
  char *res = malloc(cap);

  while (!feof(stdin)) {
    if (cap-*sz < CHUNK_SIZE) {
      cap *= 2;
      res = realloc(res, cap);
    }

    const size_t n = fread(res+*sz, 1, CHUNK_SIZE, stdin);
    *sz += n;

    if (n != CHUNK_SIZE && !feof(stdin)) {
      fprintf(stderr, "tak: fout tijdens lezen van standaard invoer.\n");
      exit(1);
    }
  }

  return res;
}

int entry_tak(int argc, char **argv) {
  char **args = parse_options(argc, argv);
  if (*args == NULL) {
    size_t sz = 0;
    char *data = read_stdin(&sz);

    struct state state = { .buf = data, .sz = sz };
    process(state);

    free(data);
  } else {
    while (*args != NULL) {
      struct map *map = open_map(*args);
      if (map == NULL) {
        return 1;
      }

      struct state state = { .buf = map->addr, .sz = map->sb.st_size };
      process(state);

      close_map(map);
      args++;
    }
  }

  return 0;
}